The present invention relates to a charged particle beam lithography apparatus for forming a pattern on a semi-conductor memory by utilizing a charged particle beam, and relates to a projection mask used for said charged particle beam lithography apparatus.
A conventional charged particle beam lithography apparatus, especially an electron beam lithography apparatus is used for research and development as an exposure apparatus for exposing a minute pattern referring to its high resolution. In the mass-production of the devices however, throughput of the charged particle beam lithography apparatus is low compared with that of an optical exposure apparatus, and the cost performance thereof is inferior.
Late years, a cell projection exposure method by which patterns are repeatedly loaded on a stencil mask beforehand, and the exposure is performed in a high reduction rate by deflecting optically so as to select the pattern, attracts attention. For example, such method is indicated in Japanese Patent Laid-open No. 6-163377. As in this cell projection exposure method, the complicated shape patterns are exposed together, a shot number is reduced largely, and high throughput may be obtained.
Furthermore, this cell projection exposure method is possible to expose in high accuracy too, because there is not a measurement setting error (by location gap of mask) as in a variable shaped beam type exposure beam formation method (Japanese Patent Laid-open No. 4-100208), in which the pattern that should be exposed is formed by overlapping two or more masks.
However, the cell projection exposure method has a problem as that only several ten patterns having exposure area of practically used several um are obtained to be selected. In order to increase the pattern number, a complicated pattern selecting deflection system which is capable to be deflected with a great angle becomes to be needed, furthermore, there is a problem in accuracy such as distortion of a stencil pattern and deterioration of matching accuracy and switching accuracy between mutual figures, because of aberration by an optical separating axis, deflection response, and increase of drift.
Moreover on a mask board top, in order to form a pattern which exceeds a selection range of the optical system, a drive mechanism as indicated in Japanese Patent Laid-open No. 7-183191 may be arranged, it takes an enough time for selecting the pattern by driving the mechanism, and there arises a problem in order to obtain the high throughput.